Question

Fill ups
1. In a _ , atoms are held together by strong forces.
2. At present, _ elements are known.
3. _do not have a fixed composition.
4. The valency of argon is _.
5. In a chemical equation, the _ are always written on the left-hand side.

Answer 1

1.molecule

2.118

3mixture

4.zero

5.reactants.

Answer 2

Answer:

molecules

118

mixture

zero

rectants